1. Brief Description of the Prior Art
Efforts to provide better dynamic balancing in caps for diesel engine exhaust pipes have taken various forms. Thus, in Stade et al U.S. Pat. No. 2,983,216, a rain cap for an engine exhaust pipe is provided, and this cap is of the gravity actuated-type in which the cover member is adapted to fit over the open end of the stack or exhaust pipe, and carries a counter-balancing section or portion which is pivotally supported in a way and at a location such that the cap tends, by reason of the shift of the center of gravity, to reseat or close when the exhaust gases are not acting on the cap to open it. This cap is susceptible, however, to opening under wind pressure, or the pressure of air developed as the tractor upon which the cap is mounted is carried over the road on a transport vehicle if the cap is faced in an improper direction. In the full closed position, the cap extends horizontally across the upper end of the exhaust pipe, and it is therefore necessary for the cap to open through almost 90.degree. in order for it to achieve a fully open position. This requires the exertion of a greater opening force from the exhaust gases which are being vented through the exhaust pipe, and can result in an undesirably high level of back pressure being exerted on the exhaust gases attempting to pass through the exhaust pipe.
Bauerschmidt U.S. Pat. No. 3,523,499 discloses a weather cap construction for an exhaust pipe. The weather cap is held on the exhaust pipe by a collar which is closed about the exhaust pipe by a suitable clamping bolt. In the Bauerschmidt cap, the pivoted closure element is supported for pivotation about a pivotal axis which is displaced laterally from the vertical axis of the exhaust pipe by a substantial distance, and when the cap is in its elevated, fully opened position, it exerts essentially no back pressure on the gases passing from the exhaust pipe. It must, however, open through an angle which is almost 90.degree., and therefore in the initial phase of the opening arc, an undesirable amount of back pressure may be exerted on the exhaust gases. A positive stop is provided to limit how far the crank upon which the closed cap is carried will open in its full open position, and this positive stop is in a position such the center of gravity still remains inside the pivotal axis. The crank arm will therefore fall, under the influence of gravity, to a closed position, once the exhaust gases cease to be vented through the exhaust pipe.
In De Penning U.S. Pat. No. 3,363,537, a tractor exhaust pipe cover is illustrated and described. The cover depicted includes a cap which pivots into, and away from, a horizontal plane representing the position of closure of the cap. The cap carries reflector devices in the form of a pair of plate like reflectors mounted on the opposite side of the pivotal axis of the cap structure from the cap plate proper. These reflectors afford some weight which assists the cap in opening in response to the force exerted by the upwardly moving exhaust gases.
Other types of exhaust cap structures are those which are depicted and described in Taylor U.S. Pat. No. 2,494,016; Burger U.S. Pat. No. 3,788,072 and Lukes U.S. Pat. No. 2,508,615.
2. Brief Description of the Present Invention
The present invention is an improved, dynamically balanced protective cap which is useful on the exhaust pipes of diesel engines for the purpose of preventing dust, debris and rain from entering the exhaust pipe, and thereby fouling the engine or preventing smooth running of the engine. The protective cap also is constructed so that the engine is protected from wind force acting deleteriously upon any turbocharger that may be a part of the engine, and be accesible to the down draft of wind entering the exhaust pipe and proceeding downwardly toward the engine.
The protective cap of the invention includes a tubular element by which the cap assembly in its entirety is secured to a pipe which projects in a vertical direction from a diesel engine for the purpose of venting engine exhaust gases to the atmosphere. A closure flap assembly is pivotally secured to the tubular element for pivotation about a horizontal axis in undergoing opening and closing movement with respect to the exhaust pipe upon which the protective cap is mounted. The tubular element is cut through at an angle or on a bias, so that the opening at the upper end of the exhaust pipe is angulated with respect to the vertical. Because of this, a closure plate which forms a part of the closure flap assembly can lie at an angle against the upper edge of the exhaust pipe which surrounds the discharge opening, and this closure plate need only open through an angle of about 40.degree. to achieve its fully open position. This aids in obviating the development of undesirable back pressure in the pipe and at the exhaust port of the engine at a time when the engine is running and exhaust gases are being vented through the pipe past the closure plate.
The closure plate has a pair of parallel balancing plates secured to the opposite sides of the closure plate and located on opposite sides of the tubular element. These balancing plates preferably lie in spaced parallel planes. The parallel balancing plates function to aid in distributing the weight and in translating the center of gravity of the moveable closure flap assembly in such way that the closure flap can be easily opened and easily closed when the exhaust gases terminate their flow through the exhaust pipe. Each of the parallel balancing plates carries a bearing sleeve which receives a stub axle, or other pivotal support element, which is secured to the tubular element. A pair of horizontally spaced, monoplanar wind vanes are secured to aligned edges on the two balancing plates, and each preferably extends normal to the respective balancing plate, with the two wind vanes preferably located in coplanar alignment with each other.
The dynamically balanced protective cap of the invention, as thus constructed, avoids chattering caused by rapidly opening and closing in a cylical motion at a time when the engine is running, and exhaust gases are being vented through an exhaust pipe carrying the cap.
Another important object of the invention which is achieved by the structure utilized is the obviation of opening of the pivoted closure flap assembly under the force developed by an artifical or natural air movement developed either when the engine upon which the protective cap is mounted is standing stationary, or is being towed by means of an over-the-road vehicle.
An additional object of the invention is to provide a dynamically balanced protective cap for mounting on an exhaust pipe of a diesel engine, which cap requires relatively little movement to move from its full closure position to a fully opened position, and requires relatively little exhaust gas pressure in order to achieve this opening, thereby reducing the propensity of such caps to cause an undesirable back pressure acting downwardly through the exhaust pipe to the location of the exhaust ports of the engine.
A further object of the invention is to provide a dynamically balanced protective cap for the exhaust pipe of a diesel engine, which cap is characterized in having relatively few moving parts, and in having a relatively long and trouble free operating life.